1. Field of the Invention
The present invention is generally related to a cone clutch, and, more particularly, to a cone clutch with grooves formed in its clutch faces which are generally straight and which provide an efficient evacuation path for oil when the clutch face moves into contact with an opposing surface.
2. Description of the Prior Art
Cone clutches are used in many different applications. Typically, a cone clutch is provided with one or more friction faces. Each friction face is generally shaped as a frustum of a cone to provide a tapered friction surface that is engaged by another rotating member. Cone clutches are used extensively in certain types of marine propulsion systems.
U.S. Pat. No. 4,257,506, which issued to Bankstahl on Mar. 24, 1981, discloses a shift linkage for cone clutch. The male cone member of a cone clutch mechanism has two springs, each encircling cam faces on the male cone member and bearing against the forward and reverse clutch gears, respectively, to bias the cone member away from its center or neutral position toward either the forward or reverse clutch gear. An eccentric roller on the shift actuator shaft engages with a circumferential groove in the male cone member to provide a vibrating force against the member for shifting. The shift means uses a cam and bell crank mechanism to convert axial movement of the shift control to rotary movement of the actuator shaft.
U.S. Pat. No. 4,244,454, which issued to Bankstahl on Jan. 13, 1981, discloses a cone clutch mechanism which has its forward and reverse clutch gears supported by bearings mounted on the housing, with a main shaft supported by bearings mounted on the housing in the same plane as the forward and reverse gear bearings. The male cone member is biased by two springs, each encircling cam faces on the member and bearing against the forward and reverse clutch gears, respectively, to bias the cone member away from its center or neutral position.
U.S. Pat. No. 4,630,719, which issued to McCormick on Dec. 23, 1986, discloses a torque aided pulsed impact shift mechanism. A cone clutch sleeve on a main shaft is moved axially between forward and reverse counter-rotating gears by a yoke having mirror-image oppositely tapered cams on opposite sides thereof which are selectively rotatable to engage eccentric rings on the forward and reverse gears. The engagement drives the yoke away from the one engaged gear and toward the other gear to in turn drive the clutch sleeve out of engagement with the one gear such that torque applied through the cam-engaged gear ring assists clutch disengagement of the one gear such requisite shift force decreases as speed and torque increases. The eccentric face surface of each ring actuates the yoke and drives the sleeve member out of engagement with the one gear and into engagement with the other gear with a pulsed impact hammer effect due to the eccentricity of the face surface as it rotates in a circumferential plane about the main shaft. U.S. Pat. No. 4,679,682, which issued to Gray et al on Jul. 14, 1987, discloses a marine drive shift mechanism with detent canister centered neutral. A marine drive is provided with a shift mechanism including a detent canister assembly. A cylindrical canister contains a ball biased by a pair on concentric springs into engagement with a shift lever arm to center the latter in a neutral position. The canister assembly is a self-contained modular unit inserted into the marine drive housing. The cylindrical canister has a left end wall with an aperture therethrough and has an open right end containing the ball. The first spring bears at its right end against the ball and extends axially leftwardly through the aperture in the left end wall of the canister and bears at its left end against the housing.
U.S. Pat. No. 4,869,121, which issued to Meisenburg on Sep. 26, 1989, discloses a marine propulsion unit with an improved drive shaft arrangement. A marine propulsion unit is provided wherein the main drive shaft includes an integrally formed annular portion of enlarged diameter at the location of a previously utilized lower groove and keepers. The enlarged diameter portion increases the mass and strength of the shaft at a position subject to substantial torque forces, thus substantially eliminating the problems of shaft fracture or breakage. In addition, the enlarged diameter portion is formed in the shape of a thrust collar so that the shaft can be accommodated by the previous known shaft mounting elements without redesign of the latter.
U.S. Pat. No. 6,523,655, which issued to Behara on Feb. 25, 2003, discloses a shift linkage for a marine drive unit. The shift linkage is provided with a groove that is aligned along the path which is nonperpendicular to an axis of rotation of the shift-linkage. The groove, and its nonperpendicularity to the axis of rotation, allows a detent ball to smoothly roll and slide along the groove. This relationship helps to maintain the shift linkage in a desired vertical position as it passes from one gear selection position to another.
U.S. Pat. No. 6,062,360, which issued to Shields on May 16, 2000, discloses a synchronizer for a gear shift mechanism for a marine propulsion system. Using a hub and a sleeve that are axially movable relative to an output shaft but rotationally fixed to the shaft and to each other, the gear shift mechanism uses associated friction surfaces to bring the output shaft up to a speed that is in synchronism with the selected forward or reverse gear prior to mating associated gear tooth surfaces together to transmit torque from an input shaft to an output shaft. The friction surfaces on the forward and reverse gears can be replaceable to facilitate repair after the friction surfaces experience wear.
The United States patents described above relate to the use of cone clutches in conjunction with marine propulsion systems. It should be understood that cone clutches are also used in many non-marine applications.
U.S. Pat. No. 6,261,202, which issued to Forrest et al on Jul. 17, 2001, describes a cone clutch structure having recessed areas for use in a limited slip differential. A limited slip differential having at least one cone clutch element for frictionally engaging an interior surface of the rotatable differential casing is provided. The cone clutch element has a plurality of clutch engagement surfaces which are disposed about the outside surface of the cone clutch element. Recessed areas are interposed between the clutch engagement surfaces. The total clutch engagement surface is reduced to between 5% and 15% of the total engagement and recessed surface area of the clutch element to improve the performance of the differential at low temperatures.
It is generally known to provide grooves in clutch surfaces. U.S. Pat. No. 5,101,953, which issued to Payvar on Apr. 7, 1992, describes a high capacity viscous pumping groove pattern for a wet clutch. A groove pattern for the paper-based friction facing on a wet clutch is provided to equalize the surface temperature of the friction facings and thus increase the thermal capacity of the clutch where there is continuous slippage. The groove pattern includes one or more continuous annular grooves dividing the friction area into two or more annular bands and a plurality of cross grooves in each bank which are angled with respect to a radius of the facing. The angled cross grooves increase in number in each band from the inner band to the outer band. The angled cross grooves extend at an acute angle, such as 10-50 degree, to the radius. Slip of the friction pair of plates causes a viscous pumping action. The cross groove angle in each band of the facing is preferably different so as to keep all of the grooves filled with cooling oil.
U.S. Pat. No. 4,924,984, which issued to Kennedy on May 15, 1990, describes a quick pump-out clutch plate for a viscous fluid clutch. A fan clutch assembly for a vehicle includes a clutch plate rotatably driven by an input shaft. The clutch plate includes a plurality of concentric, annular lands and grooves which are mated with complementary lands and grooves of a clutch body to form a shear zone. A plurality of passages are provided in the clutch plate lands and grooves for directing fluid from a reservoir to the shear zone. A plurality of radial channels are provided in the clutch plate lands and grooves to expel fluid from the shear zone and to a receiving chamber of the clutch plate assembly. Each channel is aligned with and leads radially outwardly from a respective passage. Preferably, each groove includes an aligned notch provided on the circumference of the clutch plate. The notch includes a mouth on the surface on the clutch plate adjacent the lands and grooves and an exit on the surface of the clutch plate adjacent a receiving chamber. An angled wall provided with each notch directs fluid from a channel to the receiving chamber of the plate assembly.
U.S. Pat. No. 4,763,765, which issued to Black on Aug. 16, 1988, describes a cone clutch transmission. A drive member such as a gear of a pulley cooperates with a pair of clutch elements, each of which has a splined connection with a shaft. One clutch element is axially fixed. The other is shiftable through a small distance toward and from the fixed one. Each clutch element has a conical surface concentric to the shaft that tapers oppositely to the conical surface on the other. The driveshaft has an inner periphery of larger diameter than the shaft and has oppositely tapering conical surfaces that respectively mate with the conical surfaces on the clutch elements, which thus at all times maintain the drive member coaxial with the shaft and confine it against axial shifting. An actuator urges the shiftable clutch element towards the fixed one to engage the clutch elements with the drive member. A spring biases the clutch elements apart so that the mating conical surfaces can serve as bearings lubricated by oil delivered through the shaft.
U.S. Pat. No. 4,545,469, which issued to Yogome et al on Oct. 8, 1985, describes a cone clutch. The disclosure describes a cone clutch comprising an axially unslidable rotation shaft, a cone body connected to the rotation shaft through a helical spline, adapted to be axially shifted by a shifter or the like, and provided at the outer periphery with a pair of conical faces for frictional engagement, a pair of cone cups disposed at both sides of the cone body, carried rotatably and axially slidable on the rotation shaft, and provided with a pair of conical faces operable to frictionally engage with the faces of the cone body respectively, rotation forces transmitting mechanism for transmitting rotation forces in respectively opposite directions to the cone cups, and spring mechanism disposed between the rear sides of the cups for forcing the rear faces of the cone cups toward the cone body, respectively.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
In order to provide consistent and predictable operation of a cone clutch, it would be helpful if a system or structure could be provided which allows efficient evacuation of oil from the clutch faces in a repeatable and predictable manner. It would also be significantly beneficial if a cone clutch could be provided which is not subject to variability of operation as a result of slight variations in manufacturing which may cause slight differences in the structure of the clutch face and its associated grooves.
A clutch component, made in accordance with the preferred embodiment of the present invention, comprises a first clutch face having a first inner edge. The first inner edge is generally circumferential, in a particularly preferred embodiment, and the first clutch face is rotatable about an axis of rotation which is generally perpendicular to the first inner edge. It also comprises a first plurality of grooves formed in the first clutch face, wherein each of the first plurality of grooves is formed as a generally straight line between a first inner terminus and a first outer terminus. The first inner terminus of each of the first plurality of grooves is disposed proximate the first inner edge, with each of the first plurality of grooves extending from the first inner edge at a first preselected angle between 15 degrees and 75 degrees.
In a particularly preferred embodiment of the present invention, the first preselected angle is between 15 degrees and 45 degrees. One particular embodiment of the present invention incorporates a first preselected angle which is generally equal to 30 degrees.
A first outer edge of the first clutch face is also provided in a particularly preferred embodiment of the present invention. The first outer edge is generally circumferential and the first clutch face is disposed between the first inner and outer edges. The first outer terminus of each of the first plurality of grooves can be disposed proximate the first outer edge. The diameter of the first outer edge is less than the diameter of the first inner edge and, as a result, the first clutch face is shaped as a frustum of a cone.
In a typical application of the present invention, a second clutch face is provided which is similarly structured to the first clutch face, but facing in an opposite direction. The first and second clutch faces are supported by a common structure, with the first and second inner edges being disposed toward each other and the first and second outer edges being disposed to face away from each other. In one embodiment of the present invention, each of the first and second plurality of grooves has a bottom surface that is generally rounded in cross-section. The first plurality of grooves comprises less than 30 percent of the total area of the first clutch face in a preferred embodiment of the present invention. Similarly, the second plurality of grooves comprises less than 30 percent of the total area of the second clutch face.